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Table Of Contents

Add an SSH Key to GitHub

This guide explains how to create an SSH key and add it to GitHub so you can access repositories without using a password.

Linux / macOS

1. Check if you already have an SSH key

Open a terminal and run:

ls -al ~/.ssh

Look for files like:

id_ed25519
id_ed25519.pub

If they exist, you can reuse them. Otherwise create a new key.

2. Generate a new SSH key

Run:

ssh-keygen -t ed25519 -C "your_email@example.com"

Explanation:

You’ll see prompts like:

Enter file in which to save the key:
/home/you/.ssh/id_ed25519

Press Enter to accept the default.

Then optionally enter a passphrase for extra security.

This creates:

~/.ssh/id_ed25519
~/.ssh/id_ed25519.pub

3. (Optional) Start the SSH agent

This step is recommended but not always required.

Start the SSH agent:

eval "$(ssh-agent -s)"

Example output:

Agent pid 1234

4. Add the key to the SSH agent

ssh-add ~/.ssh/id_ed25519

This allows the key to be reused without entering the passphrase repeatedly.

5. Copy the public key

Display the public key:

cat ~/.ssh/id_ed25519.pub

Copy the entire output.

Example:

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAI... your_email@example.com

6. Add the key to GitHub

  1. Go to GitHub → Settings
  2. Select SSH and GPG keys
  3. Click New SSH key
  4. Fill in:

Title

My Laptop

Key

Paste your copied key.

  1. Click Add SSH key

7. Test the connection

ssh -T git@github.com

Expected output:

Hi username! You've successfully authenticated...

8. Clone repositories using SSH

Instead of the HTTPS URL:

https://github.com/user/repo.git

Use the SSH URL:

git@github.com:user/repo.git

Example:

git clone git@github.com:user/repo.git

Windows

The steps are similar but use PowerShell or Git Bash.

1. Check if you already have an SSH key

Open PowerShell and run:

ls $env:USERPROFILE\.ssh

Look for:

id_ed25519
id_ed25519.pub

If they exist, you can reuse them.

2. Generate a new SSH key

Run:

ssh-keygen -t ed25519 -C "your_email@example.com"

When prompted for the file location:

C:\Users\YourUser\.ssh\id_ed25519

Press Enter to accept the default.

Optionally set a passphrase.

3. Start the SSH agent

Enable and start the Windows SSH agent:

Get-Service ssh-agent | Set-Service -StartupType Automatic
Start-Service ssh-agent

4. Add the key to the SSH agent

ssh-add $env:USERPROFILE\.ssh\id_ed25519

5. Copy the public key

Display the key:

type $env:USERPROFILE\.ssh\id_ed25519.pub

Copy the entire output.

Example:

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAI... your_email@example.com

6. Add the key to GitHub

  1. Open GitHub in your browser
  2. Go to Settings
  3. Select SSH and GPG keys
  4. Click New SSH key
  5. Paste your copied key
  6. Click Add SSH key

7. Test the connection

Run:

ssh -T git@github.com

Expected output:

Hi username! You've successfully authenticated...

Troubleshooting

Check if the SSH agent is running:

ssh-add -l

Possible outputs:

The agent has no identities.

or

Could not open a connection to your authentication agent.

If needed, start the agent and add the key again.